In the war against terrorism, because of the increasing explosive force of IEDs (Improvised Explosive Devices) and other explosive devices used by terrorists, it has become desirable to provide more and more armor for military and security vehicles, to the point where the doors of some such vehicles weigh hundreds of pounds. If such a vehicle is stopped on an incline, an occupant may struggle to open the door, and in some cases may not be able to open the door at all.
In response, it has become necessary to develop motorized mechanisms for providing assistance in opening such doors.
Such doors have typically been provided with a primary door latch, including a tongue portion that is forced downward to an open position as the door is closed, and when the door closes the tongue springs back to its up position, so that the latch is then in its closed position and holds the door closed. To open the door a handle is used, which retracts the tongue, placing the latch in the open position and allowing the door to be pushed or pulled open.
Such latches for a door of a vehicle are intended to hold the door closed even in case of a violent explosion. Apparently with such a goal in mind, the latches have been designed so as to require significant force to close them, typically 40-90 pounds of spring force must be overcome in pushing the tongue of such a latch to the down position.
As the doors of such vehicles are increasingly more heavily armored and thus weigh more, the significant force required to place a latch of such a door in the open position by pushing or pulling on the open door in order to close it, imposes an additional, significant load on motorized door assist mechanisms.
What is needed is a latch that can be placed in a position allowing a door to be closed, without requiring undue force.